It is sometimes desirable to separate particulates from a solution. It is well-known to use a centrifuge to separate particulates from a solution. As known in the art, a centrifuge is a device driven by a motor that rotates an object about a fixed axis, applying a centrifugal force perpendicular to the axis of rotation to separate an initial solution, or fluid product into discrete components.
Blood is a biological fluid product that can be characterized as a suspension of particles in a fluid. Blood primarily includes plasma, white blood cells, platelets, red blood cells, and other particulates present in different ratios and having different densities. When a blood sample is centrifuged, discrete layers are formed according to their densities. The least dense particulates will separate to form a top layer and the most dense particulates will separate and form a bottom layer. After blood is centrifuged a top layer is formed that is substantially plasma, a bottom layer is formed that is substantially red blood cells, and a middle layer is formed that is known in the art as a “buffy coat.” The buffy coat contains white blood cells and platelets with an amount of plasma and red blood cells. It is often desirable to isolate the buffy coat for various applications.
It is sometimes desirable to adjust the ratio of red blood cells present in the buffy coat. However, many prior art devices are configured such that adjusting the ratio of red blood cells in the buffy coat requires several steps and is cumbersome to achieve. Also, many prior art devices are configured such that particulate residue builds on the sidewalls over time, reducing optimization of a desired concentrate.
In the same vein, it is sometimes desirable to adjust the ratio of white blood cells in the buffy coat. White blood cells are the cells of the immune system that aid in protecting against infectious disease and foreign invaders in the human body. More specifically, white blood cells help the body to fight infections by attacking bacteria, viruses, and germs that invade the body. White blood cells are ultimately derived from stem cells in the bone marrow and circulate throughout the bloodstream.
The number of white blood cells present in blood is often an indicator of disease. For example, a number of diseases trigger a response by the immune system and cause an increase in the number of white blood cells, while other conditions may affect the production of white blood cells by the bone marrow or the survival of white blood cells in circulation. As such, one reason that it is desirable to isolate the buffy coat is to evaluate a blood sample in order to monitor diseases and recommend certain treatment protocols based on the white blood cell count. Choosing the appropriate concentration of white blood cells can be an important aspect of a patient's successful recovery.
Unfortunately, known methods of centrifugation result in a buffy coat layer that is minimal in comparison to the overall volume of a blood sample, thus making the buffy coat difficult to analyze. In addition, many prior art methods of centrifugation do not allow a physician to selectively choose the concentration of white blood cells present in the buffy coat layer. In the same vein, such methods of centrifugation do not provide the physician with the ability to selectively alter the presence of stem cells obtained from a bone marrow sample for reintroduction at a patient's injury site. Furthermore, many prior art devices include numerous moving parts that are difficult to operate and which are prone to user error. Therefore, a need exists to overcome the problems with the prior art as discussed above and that reduces residue build-up on the sidewalls, optimizes the concentrate of a desired layer(s), increases fluid exchange efficiency, and provides a more convenient device and method of adjusting ratios of particulates in a desired layer.